Slapping sorceror levels on a rakshasa

[Douglas Muir 406]

Since the rak already casts as a 7th level sorceror, adding more sorceror levels would build on that, right? So a rakshasa / sorc 2 would cast like a 9th level sorceror? And the rak's CR would increase by 1 for every sorceror level added?

Additional question: presumably a rak could qualify for prestige classes, yes?

Doug M.

[BEGS]

yes
yes
probably yes

[Greystaff]

Necromancer's Grimorie "Faces of the Rakshasa" has a great concept for the rakshasa as a PC/NPC if you're looking for inspiration.